American Board of Internal Medicine (ABIM) Certification Practice Exam

In what circumstances should a diagnosis of FUO be made?

1. After 4 weeks of fever without diagnosis

2. After 3 outpatient visits or 5 days in the hospital

3. After 2 visits in outpatient and 5 days in hospital

4. After laboratory studies are completed

The correct answer is: After 2 visits in outpatient and 5 days in hospital

A diagnosis of fever of undetermined origin (FUO) should be considered after a patient has undergone a certain threshold of investigation without a definitive cause being identified. The criteria generally accepted for categorizing a fever as FUO includes the requirement of persistent fever lasting at least 3 weeks that has been evaluated by a healthcare provider. Specifically, this evaluation typically involves at least two outpatient visits and/or a minimum of 5 days of hospitalization where thorough assessments and tests are conducted to determine the cause of the fever. In this context, the rationale for recognizing option C as the correct answer lies in the specific criteria it meets regarding the duration of symptoms and the level of medical care provided. By specifying two outpatient visits along with five days of hospitalization, it aligns with the established clinical guidelines for diagnosing FUO, ensuring that a comprehensive evaluation has been made before drawing the conclusion that the fever remains unexplained. The other options either do not meet the established criteria for FUO diagnosis or partly fulfill it in a manner not supported by typical medical guidelines. Thus, option C provides a clear and structured approach to diagnosing FUO while emphasizing the need for thorough investigation across multiple healthcare encounters.